Semiconductor device

ABSTRACT

A semiconductor device according to an embodiment comprises a substrate, an epitaxial layer on the substrate, and a cluster including a plurality of particles disposed on the epitaxial layer, the particles being disposed to be apart from each other, and contacting the epitaxial layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the U.S. national stage application of InternationalPatent Application No. PCT/KR2015/008022, filed Jul. 31, 2015, whichclaims priority to Korean Application No. 10-2014-0101511, filed Aug. 7,2014, the disclosures of each of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

The embodiment relates to a semiconductor device.

BACKGROUND ART

Gallium nitride (GaN) materials with broad energy bandgap hascharacteristics such as superior forward characteristics, a highbreakdown voltage, and a low intrinsic carrier density, thecharacteristics being suitable for power semiconductor devices such aspower switches.

There is a Schottky barrier diode, a metal semiconductor field effecttransistor, or a high electron mobility transistor (HEMT), etc., as apower semiconductor device.

In the case of such a semiconductor device, since the variation width ofthe leakage current is uneven, the breakdown voltage is low and thecharacteristics of the device cannot be predicted so that thereliability of the device is low.

DISCLOSURE Technical Problem

The embodiment provides a semiconductor device having superior breakdownvoltage characteristics.

Technical Solution

A semiconductor device according to an embodiment may include asubstrate; an epitaxial layer on the substrate; and a cluster electrodeincluding the plurality of particles disposed on the epitaxial layer,the particles being disposed to be apart from each other, and contactingthe epitaxial layer.

The plurality of particles may include a shape of at least one ofspherical, hemispherical, or polyhedral.

The semiconductor device may further include a first oxidation layerdisposed in a wedge shape between the plurality of particles and theepitaxial layer. Alternatively, the semiconductor device may furtherinclude first oxidation layers disposed between the plurality ofparticles and the epitaxial layer and contacting at least one of theparticles or the epitaxial layer.

The separation distance between the plurality of first oxidation layersmay be the same as an average diameter of each of the plurality ofparticles. Alternatively, a separation distance between the plurality offirst oxidation layers may be greater than zero and smaller than severalhundreds of micrometers.

The semiconductor device may further include a second oxidation layerdisposed between the particles and on the epitaxial layer. The secondoxidation layer may be disposed to be apart from or to contact theplurality of particles.

The second oxidation layer may have a plate-like cross-sectional shape.

The semiconductor device may further include a second oxidation layerdisposed on the epitaxial layer between the plurality of first oxidationlayers.

The first and second oxidation layers may be integrally formed.Alternatively, the first and second oxidation layers may be disposed tobe apart from each other.

The semiconductor device may further include a lower electrode disposedon a bottom surface of the substrate.

The semiconductor device may further include the plurality of wiresconnected to the plurality of particles, respectively.

The plurality of the particles may be disposed at equal intervals or atdifferent intervals from each other.

The plurality of the particles may have a planar shape arranged in amatrix form, in a honeycomb form, or in random form.

Each of the particles may include at least one of Ag, Al, Au, Cr, Cu,Ni, Ti, or W.

At least one of the epitaxial layer or the substrate may include atleast one of group IV semiconductor, group III-V compound semiconductor,or group II-VI compound semiconductor.

A volume of each of the plurality of particles may be several μm³ toseveral hundred μm³.

The epitaxial layer may include a light emitting structure, wherein thelight emitting structure may include a first conductive semiconductorlayer, an active layer, and a second conductive semiconductor layerdisposed on the substrate.

The epitaxial layer may include a channel layer on the substrate; and anelectron supply layer disposed on the channel layer and forming aheterojunction interface with the channel layer, wherein the clusterelectron may be disposed on the electron supply layer.

The first oxidation layers may be smaller in size than the particles,and the second oxidation layer may be smaller in size than the particle.

Advantageous Effects

The semiconductor device according to the embodiment has excellentbreakdown voltage characteristics and improved withstand voltagecharacteristics because an electrode is in the form of a plurality ofparticles so that the electric field is non-concentrated and dispersed,and makes the masking and etching processes for forming the electrode tobe unnecessary, thereby reducing the process cost and shortening theprocess time.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a cross-sectional view of a semiconductor device accordingto an embodiment.

FIG. 2 shows a cross-sectional view of the semiconductor deviceaccording to another embodiment.

FIG. 3 shows a cross-sectional view of a semiconductor device accordingto still another embodiment.

FIG. 4 shows a cross-sectional view of a semiconductor device accordingto still another embodiment.

FIG. 5 shows a cross-sectional view of a semiconductor device accordingto still another embodiment.

FIGS. 6a to 6c show plan views of a variety of semiconductor devicesaccording to the embodiment.

FIG. 7a shows a cross-sectional view and a graph relating to an electricfield of a semiconductor device according to a comparative example, andFIG. 7b shows a cross-sectional view and a graph relating to an electricfield of the semiconductor device shown in FIG. 2.

FIGS. 8a to 8d show process cross-sectional views illustrating a methodof manufacturing the semiconductor device shown in FIG. 2.

FIG. 9 shows a cross-sectional view of one application of thesemiconductor device shown in FIG. 2.

FIG. 10 shows a cross-sectional view of another application of thesemiconductor device shown in FIG. 2.

FIG. 11 shows a cross-sectional view of a light emitting device packageaccording to the embodiment.

BEST MODE

Hereinafter, exemplary embodiments will be described in order toconcretely describe the present invention and in detail with referenceto the accompanying drawings to aid in understanding of the presentinvention. However, the embodiments according to the present inventionmay be altered in various ways, and the scope of the present inventionshould not be construed as being limited to the embodiments described asfollows. The embodiments according to the present invention are intendedto provide those skilled in the art with more complete explanation.

In the following description of the embodiments according to the presentinvention, it will be understood that, when each element is referred toas being formed “on” or “under” the other element, it can be directly“on” or “under” the other element, or can be indirectly formed with oneor more intervening elements therebetween. In addition, it will also beunderstood that “on” or “under” the element may mean an upward directionand a downward direction based on the element.

In addition, the relative terms “first”, “second”, “top/upper/above”,“bottom/lower/under” and the like in the description and in the claimsmay be used to distinguish between any one substance or element andother substances or elements and not necessarily for describing anyphysical or logical relationship between the substances or elements, ora particular order.

In the drawings, the dimensions such as thicknesses and sizes of layersmay be exaggerated, omitted, or illustrated schematically for clarityand convenience of description. In addition, the dimensions ofconstituent elements do not precisely reflect the actual dimensions.

FIG. 1 shows a cross-sectional view of a semiconductor device 100Aaccording to an embodiment.

The semiconductor device 100A shown in FIG. 1 may include a substrate110, an epitaxial layer 120, and a cluster electrode 130.

The epitaxial layer 120 may be disposed on the substrate 110. Here, atleast one of the substrate 110 or the epitaxial layer 120 may include atleast one of group IV semiconductor, group III-V compound semiconductor,or group II-VI compound semiconductor. Each of the substrate 110 and theepitaxial layer 120 may be implemented in, for example, the group IVsemiconductor such as carbon (C), silicon (Si), germanium (Ge), siliconcarbide (SiC), the group III-V compound semiconductor such as galliumarsenide (GaAs), gallium nitride (GaN), and the group II-VI compoundsemiconductor such as zinc oxide (ZnO), zinc selenide (ZnSe), cadmiumtelluride (CdTe).

Also, the substrate 110 may comprise a conductive material ornon-conductive material. For example, the substrate 110 may comprise atleast one of sapphire (Al₂O₃), GaP, InP, or Ga₂O₃.

Also, the substrate 110 and the epitaxial layer 120 may comprisematerials of the same type or different type.

The cluster electrode 130 may include the plurality of particles, whichis disposed to be apart from each other, disposed on the epitaxial layer120, and electrically contact the epitaxial layer 120. Although thecluster electrode 130 may include four particles 130-1, 130-2, 130-3,and 130-4 as shown in FIG. 1, the embodiment is not limited thereto. Inanother embodiment, the number of the particles included in the clusterelectrode 130 may be greater than or less than 4.

Each of the particles of the cluster electrode 130 may include at leastone of silver (Ag), aluminum (Al), gold (Au), chromium (Cr), copper(Cu), nickel (Ni), titanium (Ti), or tungsten (W). However, theembodiments are not limited to the specific structure material of eachof the particles 130-1 to 130-4.

The plurality of the particles 130-1 to 130-4 may be disposed at equalor different intervals from each other. Referring to FIG. 1, aseparation distance L1 between the particles 130-1 and 130-2 adjacent toeach other, a separation distance L2 between the other particles 130-2and 130-3 adjacent to each other, and a separation distance L3 betweenthe other particles 130-3 and 130-4 adjacent to each other may be thesame or different.

Further, the volume of each of the plurality of particles 130-1 to 130-4may be several μm³ to several hundred μm³. However, the embodiment isnot limited to the sizes of the plurality of particles 130-1, 130-2,130-3, and 130-4.

The volumes of the plurality of particles 130-1 to 130-4 may be equal toor different from each other.

In addition, the plurality of particles 130-1 to 130-4 may have a sphereshape as shown in FIG. 1, but the embodiment is not limited thereto.That is, the plurality of particles 130-1, 130-2, 130-3, and 130-4 mayhave a shape of at least one of spheres, hemispheres, or polyhedrons.

In addition, the plurality of particles 130-1 to 130-4 may have the sameor different shapes.

In addition, the semiconductor device 100A shown in FIG. 1 may furtherinclude a lower electrode 140. The lower electrode 140 may be disposedon a bottom surface 110A of the substrate 110. The lower electrode 140may include a metal material. For example, the lower electrode 140 maybe formed of refractory metals or a mixture of these refractory metals.Alternatively, the lower electrode 140 may include at least one ofplatinum (Pt), germanium (Ge), copper (Cu), Chromium (Cr), Nickel (Ni),gold (Au), titanium (Ti), aluminum (Al), tantalum (Ta), tantalum nitride(TaN), titanium nitride (TiN), palladium (Pd), tungsten (W), or tungstemsilicide (WSi₂). However, the embodiment is not limited thereto.

FIG. 2 shows a cross-sectional view of the semiconductor device 100Baccording to another embodiment.

Unlike the semiconductor device 100A shown in FIG. 1, the semiconductorlayer 100B shown in FIG. 2 may further include a first oxidation layer150. Except for this, the semiconductor device 100B shown in FIG. 2 isthe same as the semiconductor device 100A shown in FIG. 1, and thus isdesignated by the same reference numerals and a repeated descriptionthereof is omitted or the description of FIG. 1 is substituted for thedescription of FIG. 2.

As shown in FIG. 2, the first oxidation layer 150 may be disposed in aspace between the plurality of particles 130-1 to 130-4 and theepitaxial layer 120. Here, the first oxidation layer 150 canelectrically contact at least one of the plurality of particles 130-1 to130-4 or the epitaxial layer 120.

In addition, the first oxide layer 150 may be smaller than the particles130-1 to 130-4.

In addition, the first oxidation layer 150 may be disposed in a wedgeshape stuck in an empty space between the plurality of particles 130-1to 130-4 and the epitaxial layer 120.

Further, the separation distance ‘d’ between the plurality of firstoxidation layers 150 may be the same as the average diameter (D) of theplurality of particles, but the embodiment is not limited thereto. Here,the average diameter (D) means the average of diameters of the pluralityof particles 130-1 to 130-4, and, for example, may be several tens of μmto several hundreds of μm.

When the separation distance d between the plurality of first oxidationlayers 150 is 0 or less, the trapped charge of the first oxidation layer150 increases, thereby being capable of lowering the current efficiencyand C-V characteristics. Further, when the separation distance d islarger than several hundreds of μm, the density of the plurality ofparticles 130-1 to 130-4 decreases in a given area, thereby beingcapable of lowering the current efficiency characteristic. In this case,the current density can be smaller than 200 A/cm². Therefore, theseparation distance d may be greater than 0 and less than severalhundred of μm.

FIG. 3 shows a cross-sectional view of a semiconductor device 100Caccording to still another embodiment.

Unlike the semiconductor device 100A shown in FIG. 1, the semiconductordevice 100C shown in FIG. 3 may further second oxidation layers 160A and160B. Except for this, the semiconductor device 100C shown in FIG. 3 isthe same as the semiconductor device 100A shown in FIG. 1, and thus isdesignated by the same reference numerals and a repeated descriptionthereof is omitted or the description of FIG. 1 is substituted for thedescription of FIG. 3.

The second oxidation layers 160A and 160B may be disposed between theplurality of particles 130-1 to 130-4 over the epitaxial layer 120. Atthis time, as shown in FIG. 3, the second-first oxidation layer 160A maybe disposed to be apart from the plurality of particles 130 and thesecond-second oxidation layer 160B may be disposed in contact with theparticle 130. That is, the second-second oxidation layer 160B has thesame shape as the first oxidation layer 150.

In addition, the second oxidation layers 160A and 160B may be smaller insize than the particles 130-1 to 130-4.

Alternatively, the semiconductor device 100C may include only thesecond-first oxidation layer 160A disposed to be apart from theplurality of particles 130-1 to 130-4, or only the second-secondoxidation layer 160B arranged in contact with the plurality of particles130-1 to 130-4.

FIG. 4 shows a cross-sectional view of a semiconductor device 100Daccording to still another embodiment.

Like the second oxidation layers 160A and 160B shown in FIG. 3, thesecond oxidation layer 170 shown in FIG. 4 is disposed between theplurality of particles 130-1 through 130-4 on the epitaxial layer 120.However, unlike the second oxidation layers 160A and 160B shown in FIG.3, the second oxidation layer 170 shown in FIG. 4 may have a plate-likecross-sectional shape. Except for this, the semiconductor device 100Dshown in FIG. 4 is the same as the semiconductor device 100A shown inFIG. 1 and thus is designated by the same reference numerals and arepeated description thereof is omitted.

In addition, the thickness t of the second oxidation layer 170 may be 2nm and may be a natural oxide film.

FIG. 5 shows a cross-sectional view of a semiconductor device 100Eaccording to still another embodiment.

Unlike the semiconductor device 100B shown in FIG. 2 including only thefirst oxidation layer 150, the semiconductor device 100E shown in FIG. 5may include a second-first oxidation layer 160A as well as a firstoxidation layer 150.

That is, like the first oxidation layer 150 shown in FIG. 2, the firstoxidation layer 150 shown in FIG. 5 may be disposed between theplurality of particles 130-1 to 130-4 and the epitaxial layer 120. Inaddition, like the second-first oxidation layer 160A shown in FIG. 3,the second oxidation layer 160A may be disposed over the epitaxial layer120 between the first oxidation layers 150. At this time, instead of thesecond oxidation layer 160A, the second-second oxidation layer 160B, asshown in FIG. 3, which is in electrical contact with the particles130-1, may be disposed on the epitaxial layer 120 together with thefirst oxidation layer 150.

As shown in FIG. 5, the first and second oxidation layers 150 and 160 Amay be disposed to be apart from each other. Alternatively, unlike thatshown in FIG. 5, the first and second oxidation layers 150 and 160A maybe integrally formed.

Also, the width of the aforementioned first or second oxidation layer150, 160A, or 160B may be nanometer (nm) in size.

When implemented as shown in FIG. 4 among the semiconductor devices 100Ato 100E shown in FIGS. 1 to 5, the semiconductor device may haveexcellent breakdown voltage characteristics. When implemented as shownin FIG. 2, the semiconductor device may have excellent currentefficiency.

FIGS. 6a to 6c show plan views of a variety of semiconductor devices100F, 100G, and 100H according to the embodiment.

Each of the semiconductor devices 100F, 100G, and 100H shown in FIGS. 6ato 6c may have the cross-sectional shapes similar to that of thesemiconductor devices 100A, 100B, 100C, 100D, and 100E shown in FIGS. 1to 5.

First, as shown in FIG. 6a , in the semiconductor device 100F, theplurality of particles 130 may have a planar shape arranged in a matrixform. Alternatively, as shown in FIG. 6b , in the semiconductor device100G, the plurality of the particles 130 may have a planar shapearranged in random form. Alternatively, as shown in FIG. 6c , in thesemiconductor device 100H, the plurality of the particles 130 may have aplanar shape arranged in a honeycomb form. Besides, although not shown,the plurality of particles 130 may have various planar shapes. That is,according to still another embodiment, the semiconductor device mayinclude the plurality of particles 130 having planar shapes mixed withthe planar shapes shown in FIGS. 6a to 6 c.

In addition, when the interval between the plurality of particles 130 issmall, that is, when the density of a plurality of particles is high,the on-resistance r_(ON) can be reduced and the threshold voltage Vthcan be lowered.

FIG. 7a shows a cross-sectional view and a graph relating to an electricfield (E: Electric field) of a semiconductor device according to acomparative example, and FIG. 7b shows a cross-sectional view and agraph relating to an electric field of the semiconductor device 100Bshown in FIG. 2. In the electric field graphs shown in FIGS. 7A and 7B,the abscissa axis represents the distance (x) and the ordinate axisrepresents the electric field (E).

The semiconductor device according to the comparative example shown inFIG. 7a may be composed of the substrate 110, the epitaxial layer 120,and the plate-shaped electrode 30. When the electrode 30 has this shape,the electric field is concentrated at the edge (x=x1, x=x2) of theinterface of the electrode 30. Therefore, it can be seen that the firstelectric field (E=E1) at each edge (x=x1, x=x2) is very high. As aresult, when the breakdown occurs, the semiconductor device shown inFIG. 7a may be in an inoperative state.

On the other hand, in the semiconductor device 100B according to theembodiment shown in FIG. 7b , since the cluster electrode 130 is made upof a plurality of particles 130-1 to 130-4, it can be seen that thesecond electric field E2 at each of positions (x3, x4, x5, x6) of theparticles 130-1 to 130-4 may be much lower than the first electric fieldE1, as compared with the comparative example shown in FIG. 7a . That is,since the electric field is dispersed in each of the plurality ofparticles 130-1 to 130-4, the second electric field E2 can be much lowerthan the first electric field E1. Thus, in the case of the semiconductordevice according to the embodiment, since the phenomenon ofconcentration of the electric field is prevented, the semiconductordevice 100B can have improved withstand voltage characteristics.

Hitherto, the breakdown voltage characteristics of the semiconductordevice 100B shown in FIG. 2 are only discussed. However, also in thecase of the semiconductor devices 100A and 100C to 100E shown in FIGS. 1and 3 to 5, since the electrode 130 is in the form of the plurality ofparticles 130-1 to 130-4 as in the case of the semiconductor device 100Bshown in FIG. 2, the breakdown voltage characteristic can be improvedand excellent withstand voltage characteristics can be obtained.

Hereinafter, a method of manufacturing the semiconductor device 100Bshown in FIG. 2 will be described with reference to the attached FIGS.8a to 8d . Although the manufacturing methods of the semiconductordevices 100A, 100C, 100D, and 100E shown in FIGS. 1 and 3 to 5 areomitted, the semiconductor devices 100A, 100C, 100D, and 100E may bemanufactured at the level of those skilled in the art by applying FIGS.8a to 8 d.

FIGS. 8a to 8d show process cross-sectional views illustrating a methodof manufacturing the semiconductor device 100B shown in FIG. 2.

First, referring to FIG. 8A, the lower electrode 140 and the epitaxiallayer 120 are formed at a back surface 110A and a front surface 110B ofa substrate 110, respectively. Here, the lower electrode 140 may beformed of a metal material, for example, a refractory metal or a mixtureof such refractory metals. Alternatively, the lower electrode 140 may beformed of at least one of platinum (Pt), germanium (Ge), copper (Cu),chromium (Cr), nickel (Ni), gold (Au), titanium (Ti), aluminum (Al),tantalum (Ta), tantalum nitride (TaN), titanium nitride (TiN), palladium(Pd), tungsten (W), or tungstem silicide (WSi₂).

Each of the substrate 110 and the epitaxial layer 120 may be formed ofat least one of a group IV semiconductor, a group III-V compoundsemiconductor, or a group II-VI compound semiconductor.

Next, referring to FIG. 8b , a metal thin film layer 130A is formed onthe epitaxial layer 120. The metal thin film layer 130A may be formed ofat least one of silver (Ag), aluminum (Al), gold (Au), chrome (Cr),copper (Cu), nickel (Ni), titanium (Ti), or tungsten (W).

Next, referring to FIG. 8c , the metal thin film layer 130A isheat-treated to form a cluster electrode 130 composed of a plurality ofparticles 130. For example, the metal thin film layer 130A may besubjected to Rapid Thermal Processing (RTP), Rapid Thermal Annealing(RTA), or a furnace thermal processing or the like in a temperaturerange of 100° C. to 1500° C., thereby forming the plurality of particles130 from the metal thin film layer 130A.

Next, referring to FIG. 8d , the resultant shown in FIG. 8c is oxidizedto form the first oxidation layer 150. For example, when the resultantshown in FIG. 8c is oxidized within a temperature range of 500° C. to1400° C. using a thermal wet oxidation furnace, the first oxidationlayer 150 may be formed in a wedge shape between the plurality ofparticles 130 and the epitaxial layer 120.

When the electrode 30 is formed as in the comparative example shown inFIG. 7a , a masking process and an etching process are required forforming the electrode 30. But, when the electrode 130 is formed as shownin FIG. 7b or FIG. 8c , the masking and etching processes areunnecessary. Thus, it is possible to reduce the process cost and shortenthe process time.

Meanwhile, the semiconductor devices 100A to 100E according to theabove-described embodiments can be applied to various fields. Forexample, the semiconductor devices 100A to 100E may be applied to alight emitting diode, or may be applied to the power devices such as aSchottky barrier diode, a metal semiconductor field effect transistor,and a high electron mobility transistor (HEMT).

According to one application, the semiconductor devices 100A to 100Dshown in FIGS. 1 to 5 may be vertical type Schottky diodes. In thiscase, the lower electrode 140 may correspond to the anode of theSchottky diode, and the cluster electrode 130 may correspond to thecathode of the Schottky diode. Alternatively, conversely, the lowerelectrode 140 and the cluster electrode 130 may correspond to thecathode and the anode of the Schottky diode, respectively.

According to another application, the semiconductor devices 100A to 100Eshown in FIGS. 1 to 5 may be applied to light emitting diodes. This willbe described with reference to the attached FIG. 9 as follows.

FIG. 9 shows a cross-sectional view of one application 100B-1 of thesemiconductor device 100B shown in FIG. 2.

The substrate 110, the epitaxial layer 120A, the plurality of particles130, the lower electrode 140, and the first oxidation layer 150 of thesemiconductor device 100B-1 shown in FIG. 9 correspond to the substrate110, the epitaxial layer 120, the plurality of particles 130, the lowerelectrode 140, and the first oxidation layer 150 shown in FIG. 2,respectively.

In particular, the epitaxial layer 120A may include a light emittingstructure. The light emitting structure includes a first conductivesemiconductor layer 122, an active layer 124, and a second conductivesemiconductor layer 126 disposed on the substrate 110.

The first conductive semiconductor layer 122 may be disposed between thesubstrate 110 and the active layer 124 and may be implemented incompound semiconductor. The first conductive semiconductor layer 122 maybe implemented in group III-V or II-VI compound semiconductors. Forexample, the first conductive semiconductor layer 122 may comprise asemiconductor material having a composition of In_(x)Al_(y)Ga_(1-x-y)N(0≤x≤1, 0≤y≤1, 0≤x+y≤1). The first conductive semiconductor layer 122may be doped with a first conductive dopant. When the first conductivesemiconductor layer 122 is an p-type semiconductor layer, the firstconductive dopant may include, for example, Mg, Zn, Ca, Sr, Ba, etc. asa p-type dopant.

The active layer 124 may be disposed between the first conductivesemiconductor layer 122 and the second conductive semiconductor layer126 and is a layer in which holes (or electrons) injected through thefirst conductive semiconductor layer 122 and electrons (or holes)injected through the second conductive semiconductor layer 126 meet eachother to emit light having energy determined by an inherent energy bandof a constituent material of the active layer 124.

The active layer 124 may be formed into at least one structure of asingle-well structure, a multi-well structure, a single-quantum wellstructure, a multi-quantum well MQW structure, a quantum wire structure,or a quantum dot structure.

In the active layer 124, a well layer and a barrier layer may be formedin a pair structure of any one or more of InGaN/GaN, InGaN/InGaN,GaN/AlGaN, InAlGaN/GaN, GaAs(InGaAs)/AlGaAs, and GaP(InGaP)/AlGaP,without being limited thereto. The well layer may be formed of amaterial having lower band gap energy than the band gap energy of thebarrier layer.

A conductive clad layer (not illustrated) may be formed above and/orunder the active layer 124. The conductive clad layer may be formed ofsemiconductors having higher band gap energy than the band gap energy ofthe barrier layer of the active layer 124. For example, the conductiveclad layer may include GaN, AlGaN, InAlGaN, or a super latticestructure, etc. In addition, the conductive clad layer may be doped withan n-type or p-type dopant.

The second conductive semiconductor layer 126 may be disposed over theactive layer 124 and may be formed of group III-V or II-VI compoundsemiconductors doped with a second conductive dopant. When the secondconductive semiconductor layer 126 is an n-type semiconductor layer, thesecond conductive dopant may include Si, Ge, Sn, Se, Te as an n-typedopant, without being limited thereto.

For example, the second conductive semiconductor layer 126 may include asemiconductor material having a composition of Al_(x)In_(y)Ga_((1-x-y))N(0≤x≤1, 0≤y≤1, 0≤x+y≤1). The second conductive semiconductor layer 126may include any one or more materials selected from among GaN, InN, AlN,InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP,InGaP, AlInGaP, and InP.

At this time, the lower electrode 140 serves to supply holes (orelectrons), which are the first conductivity type carriers, to the firstconductive semiconductor layer 122, and the cluster electrode 130 servesto supply electrons (or holes), which are the second conductivity typecarriers, to the second conductive semiconductor layer 126. The lowerelectrode 140 may be formed of a metal having excellent electricalconductivity and of a metal having a high thermal conductivity sinceheat generated during operation of the semiconductor device 100B-1 mustbe sufficiently dissipated.

For example, the lower electrode 140 may be made of a material selectedfrom the group consisting of molybdenum (Mo), silicon (Si), tungsten(W), copper (Cu), and aluminum (Al), or alloy thereof or may selectivelyinclude Gold (Au), copper alloy (Cu Alloy), nickel (Ni), copper-tungsten(Cu—W), a carrier wafer (e.g., GaN, Si, Ge, GaAs, ZnO, SiGe, SiC, SiGe,Ga₂O₃, etc.), etc.

The semiconductor device 100B-1 shown in FIG. 9 has a vertically-bondedstructure, but the embodiment is not limited thereto. That is, thesemiconductor devices 100A to 100E shown in FIGS. 1 to 5 may be appliedto a light emitting device (not shown) having a horizontal bonding typeor a flip chip bonding type structure.

According to still another application, the semiconductor devices 100Ato 100E shown in FIGS. 1 to 5 may be applied to power devices. This willbe described with reference to FIG. 10 attached hereto as follows.

FIG. 10 shows a cross-sectional view of another application 100B-2 ofthe semiconductor device 100B shown in FIG. 2.

The substrate 110, the epitaxial layer 120B, the plurality of theparticles 130, and the first oxidation layer 150 of the semiconductordevice 100B-2 shown in FIG. 10 correspond to the substrate 110, theepitaxial layer 120, the plurality of particles 130, and the firstoxidation layer 150 shown in FIG. 2, respectively. Unlike thesemiconductor device 100B shown in FIG. 2, the semiconductor device100B-2 shown in FIG. 10 does not include the lower electrode 140. Exceptfor this, the semiconductor device 100B-2 shown in FIG. 10 and thesemiconductor device 100B shown in FIG. 2 have the same components.

In particular, the epitaxial layer 120B may include an intermediatelayer 122, a channel layer 124, and an electron supply layer 126.

The intermediate layer 122 may be disposed on the substrate 110 and mayimpart compressive stress to the epitaxial layer 120B. When thecompressive stress applied to the epitaxial layer 120B through theintermediate layer 122 increases, the epitaxial layer 120B having arelatively large thickness may be formed. That is, since thesemiconductor device 100B-2 shown in FIG. 10 is a power semiconductordevice, in case that the thickness of the intermediate layer 122increases, the characteristics of the device may be improved forexample, the breakdown voltage (BV) of the power device increases.

According to the embodiment, the intermediate layer 122 may be a superlattice (SL) layer. Here, the super lattice layer may be a layer inwhich the wave function overlaps with other super lattice layer adjacentthereto and the interval from the adjacent super lattice layer is 3 nmto 4 nm, but, the embodiment is not limited thereto.

In some cases, the intermediate layer 122 may be omitted.

The channel layer 124 may be disposed over the intermediate layer 122,and between the intermediate layer 122 and the electron supply layer126. The channel layer 124 may be implemented as an undoped layer toenhance the mobility of electrons and may include at least one GaNlayer.

The electron supply layer 126 is disposed over the channel layer 124,helps to form the channel 123A, and serves to warp band gap energy. As alayer having a band width larger than that of the channel 123A, theelectron supply layer 126 may have a uniform polarization densitythroughout the layer. The electron supply layer 126 has a smallerlattice integer than the channel layer 124. Therefore, the electronsupply layer 126 and the channel layer 124 may form a heterojunctioninterface 125A. In this way, when the electron supply layer 126 and thechannel layer 124, the lattice integers of the electron supply layer 126and the channel layer 124 being different from each other, form theheterojunction interface 125A, the spontaneous polarization andpiezoelectric polarization are brought about due to the lattice integerdifference so that two-dimensional electron gas (2-DEG: 2-DimensionalElectron Gas), which is a channel in the channel layer 124 side at theheterogeneous junctions 125A may be generated. That is, when the gatebias is applied to the gate electrode G, the channel 123A is formed onthe channel layer 124 side at the heterojunction interface 125A. Assuch, since the electron supply layer 126 plays the role of a barrier tothe electron, the 2-DEG layer 123A may be formed in the channel layer124 at the heterojunction interface 125A.

The electron supply layer 126 may be implemented in group III-V or II-VIcompound semiconductors. For example, The electron supply layer 126 mayinclude a semiconductor material having a composition ofAl_(a)In_(b)Ga_((1-a-b))N (0≤a≤1, 0≤b≤1, 0≤a+b≤1). The electron supplylayer 126 may include a nitride semiconductor layer such as GaN, InN,AlN, InGaN, AlGaN, InAlGaN and AlInN, or at least one of AlGaAs, InGaAs,AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, or InP. For example, the electronsupply layer 126 may comprise AlGaN or Al_(x)InGaN. Further, theelectron supply layer 126 may be an undoped layer in order to improvethe mobility of electrons.

A gate electrode G, a source contact S, and a drain contact D may bedisposed on the electron supply layer 126. Each of the gate electrode G,the source contact S, and the drain contact D may be a cluster electrode130 having a plurality of particles as shown. The source contact S isdisposed on the electron supply layer 126 to be apart from one side ofgate electrode G. The drain contact D is disposed on the electron supplylayer 126 to be apart from the other side of the gate electrode G.

Each of the plurality of particles in each of the source contact S andthe drain contacts D may be formed of a metal. In addition, each of thesource contact S and the drain contact D may include the same materialas the material of the gate electrode G. Further, each of the sourcecontact S and the drain contact D may be formed of a reflectiveelectrode material having an ohmic characteristic.

The embodiment is not limited by the shape and structure of the gateelectrode G, the source contact S, and the drain contact D illustratedas an example in FIG. 10. That is, according to another embodiment, agate insulating layer (not shown) may be further disposed between thegate electrode G and the electron supply layer 126.

Hereinafter, a light emitting device package 200 including thesemiconductor device 100B-1 shown in FIG. 9 will be described withreference to FIG. 11 as follows.

FIG. 11 shows a cross-sectional view of a light emitting device package200 according to the embodiment.

The light emitting device package 200 shown in FIG. 11 may include thesemiconductor device 100B-1, a body 210, first and second lead frames212 and 214, a molding member 220, and wires 216-1, 216-2, 216-3, and216-4. The semiconductor device 100B may correspond to the semiconductordevice 100B-1 shown in FIG. 9.

The first and second lead frames 212 and 214 are electrically separatedfrom each other. The molding member 220 may be filled in the cavityformed by the body 210 to surround and protect the semiconductor device100B-1. Further, the molding member 220 may include a phosphor toconvert the wavelength of the light emitted from the semiconductordevice 100B-1.

The lower electrode 140 of the semiconductor device 100B-1 maycorrespond to the anode of the light emitting device and may beelectrically connected to the first lead frame 212 directly. At thistime, the plurality of particles 130-1, 130-2, 130-3, and 130-4 formingthe cluster electrode 130 in the semiconductor device 100B-1 maycorrespond to the cathode of the light emitting device. Alternatively,the lower electrode 140 may correspond to the cathode of the lightemitting device, and the cluster electrode 130 may correspond to theanode of the light emitting device.

At this time, the plurality of particles 130-1, 130-2, 130-3, and 130-4of the cluster electrode 130 are electrically connected to the pluralityof wires 216-1, 216-2, 216-3, and 216-4, respectively, and may beconnected to the second lead frame 214 through the wires 216-1, 216-2,216-3, and 216-4.

Alternatively, unlike FIG. 11, the lower electrode 140 is electricallyin direct contact with the second lead frame 214 instead of the firstlead frame 212, and the plurality of particles 130-1 to 130-4 may beelectrically connected to the first lead frame 212 instead of the secondlead frame 214 through each of the wires 216-1 to 216-4, respectively.

Referring to FIG. 11, it can be known that the wires 216-1, 216-2,216-3, and 216-4 are connected to each of the particles 130-1, 130-2,130-3, and 130-4 shown in FIGS. 1 to 5, respectively.

Although the present invention has been described with reference toexemplary embodiments thereof, the present invention is not limited tothe these embodiments and it should be understood that numerous othermodifications and applications which are not aforementioned can bedevised by those skilled in the art that will fall within the spirit andscope of the principles of this disclosure. For example, each componentthat is specifically shown in the embodiments can be modified andimplemented. And, it should be understood that differences related tosuch variations and applications are included in the scope of thepresent invention set out in the appended claims.

MODE FOR INVENTION

Embodiments for implementation of this disclosure have sufficientlydescribed in the above “Best Mode”.

INDUSTRIAL APPLICABILITY

The semiconductor device according to the embodiment may be used as thepower semiconductor device such as Schottky barrier diode, metalsemiconductor field effect transistor, or High Electron MobilityTransistor HEMT.

The invention claimed is:
 1. A semiconductor device, comprising: asubstrate; an epitaxial layer on the substrate; a cluster electrodeincluding a plurality of particles disposed on the epitaxial layer, theparticles being disposed to be apart from each other, and contacting theepitaxial layer; first oxidation layers disposed between the pluralityof particles and the epitaxial layer, and contacting at least one of theparticles or the epitaxial layer; and a second oxidation layer disposedbetween the particles and on the epitaxial layer, the second oxidationlayer being disposed to be apart from the plurality of particles andcontacting the epitaxial layer.
 2. The semiconductor device according toclaim 1, wherein each of the plurality of particles has a sphericalshape.
 3. The semiconductor device according to claim 1, wherein thefirst oxidation layers are disposed in a wedge shape between theplurality of particles and the epitaxial layer.
 4. The semiconductordevice according to claim 1, wherein a separation distance betweenrespective layers of the first oxidation layers is the same as anaverage diameter of the plurality of particles.
 5. The semiconductordevice according to claim 1, wherein a separation distance betweenrespective layers of the first oxidation layers is greater than zero andsmaller than several hundred micrometers.
 6. The semiconductor deviceaccording to claim 1, wherein the first and second oxidation layers aredisposed to be apart from each other.
 7. The semiconductor deviceaccording to claim 1, further comprising a lower electrode disposed on abottom surface of the substrate.
 8. The semiconductor device accordingto claim 1, wherein the plurality of the particles is disposed at equalintervals from each other.
 9. The semiconductor device according toclaim 1, wherein the plurality of the particles is disposed at differentintervals from each other.
 10. The semiconductor device according toclaim 1, wherein each of the particles includes at least one of Ag, Al,Au, Cr, Cu, Ni, Ti, or W.
 11. The semiconductor device according toclaim 1, wherein at least one of the epitaxial layer or the substrateincludes at least one of group IV semiconductor, group III-V compoundsemiconductor, or group II-VI compound semiconductor.
 12. Thesemiconductor device according to claim 1, wherein a volume of each ofthe plurality of particles is several μm³ to several hundred μm³. 13.The semiconductor device according to claim 1, wherein the firstoxidation layers are smaller in size than each of the particles.
 14. Thesemiconductor device according to claim 1, wherein the second oxidationlayer is smaller in size than each of the particles.